A prospector graphed the locations of a gold vein and all of the gold dust strikes in the vicinity. He positioned the gold vein at ( − 8 , 9 ) ( - 8 , 9 ) and the farthest gold dust strike at ( 7 1 , 9 ) . ( 7 1 , 9 ) . If each unit on the graph represents 1 m i l e , then how far away from the gold vein is the farthest gold dust strike?